Predicting university undergraduates' binge-drinking behavior: a comparative test of the one- and two-component theories of planned behavior.

This study provides a comparative test of the one- and two-component theories of planned behavior (TPB) in the context of university undergraduates' binge-drinking. Participants (N=120) self-completed questionnaire measures of all TPB constructs at time 1 and subsequent binge-drinking at time 2 (two-weeks later). The data were analyzed using a combination of path analyses and bootstrapping procedures. Both models accounted for a substantial proportion of the variation in behavior. However, the two-component TPB provided a significantly better fit to the data, with the total direct and indirect effects accounting for 90% of the variance. Intention was the only direct predictor of behavior. Instrumental attitude, affective attitude and self-efficacy had indirect effects. Although health interventions could usefully target these cognitive antecedents, simulation analyses, modeling the effects of cognition change on behavior, showed that only large-sized (0.8 SD) changes to affective attitude, or moderate-sized changes to all of these cognitions in combination were sufficient to reduce binge-drinking.